The present invention relates to an improvement of lead electric storage cells or batteries (hereinafter referred to as storage batteries).
In prior storage batteries, electrolysis of water takes place at the end of recharging or during overcharging which gives rise to evolvement of oxygen and hydrogen gases. When the battery is of an open type, it is always possible for these gases to escape from the battery to the outside. However, when the battery is of a sealed type, various countermeasures to prevent an increase in internal pressure due to the evolvement of these gases and ultimate breakage of the container have been taken such as: the use of a pressure container capable of withstanding and increase in internal pressure due to these gases, the provision of a safety valve operating when the internal pressure is abnormally increased, and chemical transformation of these gases into water by catalysts on the electrode plates.
On one hand, all storage batteries have previously used separators which are made of various microporous materials between the positive electrode plates and the negative electrode plates and are continuously arranged in a row in order to prevent contact short-circuiting between the two electrode plates. Ordinarily, the separator is composed of woody, rubbery, fibrous or synthetic resinous materials. A glass mat may be used. The use of such a separator necessarily adds to the material cost to a significant degree.